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This is a subdivision of the Oscilloscope article, discussing the various types and models of oscilloscopes in greater detail. ==Digital oscilloscopes== While analog devices make use of continually varying voltages, digital devices employ binary numbers which correspond to samples of the voltage. In the case of digital oscilloscopes, an analog-to-digital converter (ADC) is used to change the measured voltages into digital information. Waveforms are taken as a series of samples. The samples are stored, accumulating until enough are taken in order to describe the waveform, which are then reassembled for display. Digital technology allows the information to be displayed with brightness, clarity, and stability. There are, however, limitations as with the performance of any oscilloscope. The highest frequency at which the oscilloscope can operate is determined by the analog bandwidth of the front-end components of the instrument and the sampling rate. Digital oscilloscopes can be classified into three primary categories: digital storage oscilloscopes, digital phosphor oscilloscopes, and digital sampling oscilloscopes.〔"Oscilloscope Types" http://www.radio-electronics.com/info/t_and_m/oscilloscope/oscilloscope_types.php〕〔"XYZs of Oscilloscopes Primer" www.tektronix.com 03W_8605_3.pdf〕 Newer variants include PC-based oscilloscopes (which attach to a PC for data processing and display) and mixed-signal oscilloscopes (which employ other functions in addition to voltage measurement). === === (詳細はmemory, which can store data as long as required without degradation. A digital storage oscilloscope also allows complex processing of the signal by high-speed digital signal processing circuits. The vertical input is digitized by an analog to digital converter to create a data set that is stored in the memory of a microprocessor. The data set is processed and then sent to the display, which in early DSOs was a cathode ray tube, but is now more likely to be an LCD flat panel. DSOs with color LCD displays are common. The data set can be sent over a LAN or a WAN for processing or archiving. The screen image can be directly recorded on paper by means of an attached printer or plotter, without the need for an oscilloscope camera. The oscilloscope's own signal analysis software can extract many useful time-domain features (e.g., rise time, pulse width, amplitude), frequency spectra, histograms and statistics, persistence maps, and a large number of parameters meaningful to engineers in specialized fields such as telecommunications, disk drive analysis and power electronics. Digital storage also makes possible another type of oscilloscope, the equivalent-time sample oscilloscope. Instead of taking consecutive samples after the trigger event, only one sample is taken. However, the oscilloscope is able to vary its timebase to precisely time its sample, thus building up the picture of the signal over the subsequent repeats of the signal. This requires that either a clock or repeating pattern be provided. This type of oscilloscope is frequently used for very high speed communication because it allows for a very high "sample rate" and low amplitude noise compared to traditional real-time oscilloscopes. Digital oscilloscopes are limited principally by the performance of the analog input circuitry, the duration of the sample window, and resolution of the sample rate. When not using equivalent-time sampling, the sampling frequency should be at least the Nyquist rate, double the frequency of the highest-frequency component of the observed signal, otherwise aliasing occurs. Advantages over the analog oscilloscope are: *Brighter and bigger display with color to distinguish multiple traces *Equivalent time sampling and averaging across consecutive samples or scans lead to higher resolution down to µV *Peak detection *Easy pan and zoom across multiple stored traces allows beginners to work without a trigger * * This needs a fast reaction of the display (some oscilloscopes have 1 ms delay) * * The knobs have to be large and turn smoothly *Also slow traces like the temperature variation across a day can be recorded *Allows for automation. A disadvantage of digital oscilloscopes is the limited refresh rate of the screen. On an analog oscilloscope, the user can get an intuitive sense of the trigger rate simply by looking at the steadiness of the CRT trace. For a digital oscilloscope, the screen looks exactly the same for any signal rate which exceeds the screen's refresh rate. Additionally, it is sometimes difficult to spot "glitches" or other rare phenomena on the black-and-white screens of standard digital oscilloscopes; the slight persistence of CRT phosphors on analog oscilloscopes makes glitches visible even if many subsequent triggers overwrite them. Both of these difficulties have been overcome recently by "digital phosphor oscilloscopes", which store data at a very high refresh rate and display it with variable intensity, to simulate the trace persistence of a CRT oscilloscope. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Oscilloscope types」の詳細全文を読む スポンサード リンク
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